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Why Parker's VX065 is the Future of Elastomeric Materials in Aerospace
While reviewing Parker's extensive selection of material offerings, one might notice that Parker EMG does not immediately have a material that is certified to this AMS7254 specification. Parker is not alone, however. As of the time of this publication, there are actually no materials on the qualified parts list (QPL) on SAE’s website from any elastomeric material vendor. This is quite an odd situation as the existence of a specification implies an inherent need within the Aerospace for a material with these qualities. The Material engineers at Parker Hannifin have looked at the situation and are offering an alternative solution: VX065.
AMS7254 Specification
Before diving into the solution, let’s briefly explore the problem: what does the AMS7254 ask of an elastomeric material and what purpose does it serve? The stated scope and application of AMS7254 is to provide requirements surrounding perfluoroether molded O-rings and gaskets to be used between -65°F and 400°F in fuels, engine oils, hydraulic oils, and hydraulic fluids.
Perfluoroether material may also be known within the elastomer industry as AFLAS. Parker has several materials within this classification, but not with the low temperature requirements (TR-10 of -54°F) demanded by AMS7254. AFLAS’s tend to be “jack of all trades, master of none” type of compounds. Sharing some of the properties of fluorocarbon (FKM) and ethylene propylene diene monomer (EPDM) elastomers, but not to the same extent as either of the respective properties of FKM or EPDM. There are perfluorinated materials, like FFKM, which can meet the full spectrum of fluids. But like the AFLAS, they also are limited by the low temperature performance. Most FFKM have a TR-10 around +41°F, however some can get users much closer with TR-10 of -22°F.
As mentioned above, the AFLAS material family that would traditionally meet AMS7254 would be a “jack of all trades master of none”. As elastomeric technology has improved over the years, the capabilities of the EPDM offerings have also expanded. These days, out in the industry, most if not all of the elastomers that would traditionally be used anywhere on commercial aircrafts that would see this type of AS1241 fluid would be EPDM materials certified to NAS1613 Rev 6, such as Parker’s EM163. As the years have gone by, the specialization of both the EPDM materials to service these hydraulic fluids, and FKM materials such as VX065 to service the fuels, oils, and high temperature needs have removed the need for an elastomer that can moderately function under both conditions, but not excel at either.
Therefore, it is Parker's recommendation that if there's a need forr a material to meet AMS7254, it is important to dig deeper and ask what the application needs are. If you run into a situation where the primary need is for the material to be resistant to hydraulic fluids found in aircraft braking systems, fear not. Parker’s EM163 is certified to handle all current fluids found in these types of applications. However, it is most likely you will find a situation where a material would need to be compatible from -65°F – 400°F and be able to withstand fuels and hydraulic fluids, the exact type of service we expect VX065 to excel in!
This article was written by Tyler Karnes, aerospace & defense market development manager at Parker EMG.
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